Convert Json data by annotation in ssm

In the Controller class:

1.@RequestBody
function: convert the data obtained by the front end into JavaBean form

 //@RequestBody : 此时传入的 参数 user对象 为Json数据类型
 @RequestMapping("/user/modify.action")
 public  User  modifyUser(@RequestBody  User user) {
    
    
     System.out.println("user is " + user);
     final int ret = service.modifyUser(user);
        
     final User userDb = service.findUser(user.getId());
     return userDb;
 }

Pass a Json data to the Controller and

you can see that the incoming Json data is converted to JavaBean type

2.
Method 1: @ResponseBody
function: convert the data into Json and send it to the front end

 //@ResponseBody : 就是将 方法的返回值 转换 成 json串 。
 @ResponseBody
 @RequestMapping("/user.action")
 public User getOneUser(Integer id) {
    
    
     System.out.println("id is " + id);
     final User user = service.findUser(id);
     return user;
 }

It will return a user in the form of Json data.

Method 2: @RestController
role: the return value of the method in the entire Controller will be converted to the Json data type